Application of Bentonite and Zeolite to Eliminate the Hazards of Cadmium, Copper and Nickel Metals in Contaminated Soils

Soil pollution by heavy metals has serious hazards on microorganism, plants, human being and ecological environment. A laboratory experiment has been conducted by adding different doses of bentonite and zeolite to soils contaminated with cadmium, nickel and copper with 200 ppm of each and to the study the kinetics of release of these elements in DTPA extract. The parameters of Hoerl's and Elovich kinetic models were determined to compare the effect of adding zeolite and bentonite on sandy and clay soils. The obtained results indicated that the reaction occurred very fast after adding the remediation material and adsorption attained a constant value. The lower rate of the material was very effective in increasing the adsorption of the heavy metals on the material. The release of elements as a result of adding both zeolite and bentonite followed the order Cd²⁺ > Cu²⁺ > Ni²⁺. The role of zeolite was more pronounced in enhancing the adsorption of the heavy metals more than bentonite due its specific molecular structure and high surface area. Therefore it was recommended to be applied as a remediation material in polluted soils by heavy metals.